What could be draining a brand new battery along with having a brand new alternator?

Yes, you can disconnect it. May be time for a new battery though.

Do a parasitic battery drain test to find what's draining the battery

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test battery for dead cell, even new batteries are bad sometimes.if u don't have a load tester take to autoparts store they will check for u. with car running test voltage from alternator should be 13 or more volts . next test starter solenoid if stuck she will drain overnight.

The battery is only as good as the system which is charging it while you drive. Your alternator may not be charging the battery properly , OR something is draining the battery while the car is parked. Your new batttery might be defective , but I doubt it. Were you having a problem with your old battery ? If yes , then it probably was not the battery in the first place. If you have access to a voltage tester , check what voltage is when the engine is running. It should be around 14.5 , if it is below 13 , you likely have an alternator problem.

If the vehicle sit for a period of time, even over night and it won't start with the new battery and alternator, you have a dead short drawing voltage from the battery until it goes dead. Disconnect the positive terminal from the battery and connect a test light to the cable and touch the battery positive post with the other end of the tester. If the tester lights up, you have a draw on the battery causing it to go dead. Now you need to pull 1 fuse at a time while the tester is connected to see when the light goes out. When it dies, that is the circuit that needs to be traced to find the faulty switch, bard wire or whatever is the cause. Good luck.

Generally, you can check and test alternator with this procedure...

1. Clean the positive and negative battery terminals to ensure a good connection with the tester's clamps.
2. Connect the positive and negative clamps to the appropriate battery terminals. The clamps must make firm contact with the battery terminals or the test results will be inaccurate or the tester may not work at all.
3. Turn the tester on and choose the option for "full charging system test." This will test your battery, starter and alternator and provide the most accurate picture of the problem.
4. Follow the directions on the tester's screen. These instructions will include cranking the vehicle after the battery test is performed, holding the engine at a certain RPM range and turning on certain accessories.
5. Read the results displayed on the tester's screen. The tester should scroll through the results, starting with the battery, then the starter and finally the alternator. An alternator test result showing diode ripple problems indicates a bad alternator.

Hope helps (remember rated this).

Step 2 Connect the positive and negative clamps to the appropriate battery terminals. The clamps must make firm contact with the battery terminals or the test results will be inaccurate or the tester may not work at all.

Step 3 Turn the tester on and choose the option for "full charging system test." This will test your battery, starter and alternator and provide the most accurate picture of the problem.

Step 4 Follow the directions on the tester's screen. These instructions will include cranking the vehicle after the battery test is performed, holding the engine at a certain RPM range and turning on certain accessories.

Step 5 Read the results displayed on the tester's screen. The tester should scroll through the results, starting with the battery, then the starter and finally the alternator. An alternator test result showing diode ripple problems indicates a bad alternator.

Read more: How to Test a Car's Alternator | eHow.com http://www.ehow.com/how_2079784_test-cars-alternator.html#ixzz0spTYveGJ

Sounds like a bad alternator or Voltage regulator. Get the Haynes repair manual on your vehicle and follow the directions for removing the Alternator. take the Alternator to Auto Zone or O'Rielley''s and have it tested. If it is bad you can get a new one then and install it and solve the problem. If it test good then you will need to change the Voltage regulator.

you may have gotten a bad battery,,,it happens we bought one awhile back brand new and it was no good have it tested

ignition coil not powering right

also some useful info
batterys are refurbed these days and sometimes an unlucky person can still get a dead cell battery several times even if the you bought brand new
i took mine back 4 times before i found a good one that kept its charge
dead cells dont show them selves very well on battery tests even though dead cell the tester would show good show dont think that there is something definatley wrong you could be in same ditch i was before with my batterys
alternator testers at some shops are not reliable enough i recommend a voltage tester to battery